Commercial dilithio initiators are produced from lithium and lower molecular weight dienes with C≦5, usually C4 monomers such as butadiene. Because dilithio initiators typically have limited solubility in hydrocarbon solvents, polar solvents with other modifiers are required to increase the solubility and efficacy of the initiators for polymerization. These dilithio initiators are used commercially to produce low molecular weight anionic oligomers, high molecular weight elastomers (both typically from diene and vinyl aromatic monomers), and styrene-diene-styrene block terpolymers. However, the requirement of polar solvents for dilithio initiator synthesis and application greatly restricts the control of microstructure of the diene monomer incorporation, resulting in products with high vinyl incorporation. Higher vinyl incorporation leads to high glass transition temperatures (Tg)s which further limits the application of the oligomers and polymers. As such, there is a need for developing oligomers and polymers that have low vinyl incorporation.
One such method is to develop active dilithio initiators that are more soluble than the conventional dilithio initiators derived from C≦5 dienes in non-polar solvents. Described herein are highly active dilithio initiators derived from high molecular weight dienes (C≧6), with the majority of the carbon count in a pendant chain. The use of high molecular weight dienes (C≧6) allows for the preparation of highly active dilithio initiators with a significant reduction of polar solvent required for solubility. As such, these highly active dilithio initiators result in greater control over polymer microstructure and result in useful polymers and oligomers with low vinyl incorporation.